Polymers Having N-Vinyl Amide And Hydroxyl Moieties, Their Compositions And The Uses Thereof

ABSTRACT

The invention relates to polymers derived at least from one: (A) one N-vinyl amide unit, and (B) one hydroxyl-containing acrylate unit, and to polymers derived at least from: (A) N-vinyl-2-caprolactam, and (B) one non-acrylate unit having: (i) at least one hydroxyl group, and/or (ii) at least one functional group convertible to a hydroxyl group wherein at least one group is converted to hydroxyl functionality in the final polymer product. Such polymers may exhibit degradability, e.g., in seawater or soil environments. In preferred embodiments, these polymers and compositions thereof are used in oilfield applications, such as an inhibitor of gas hydrates and/or a kinetic inhibitor of gas hydrates. The polymer can assume alternating, block, and/or random configurations of the repeating units, with at least one ester group. The chemical structure subscripts m, and n may be any integer equal to or greater than 1.

FIELD OF THE INVENTION

The invention relates to polymers derived at least from one: (A) oneN-vinyl amide unit, and (B) one hydroxyl-containing acrylate unit, andto polymers derived at least from: (A) N-vinyl-2-caprolactam, and (B)one unit having: (i) at least one hydroxyl group, and/or (ii) at leastone functional group convertible to a hydroxyl group wherein at leastone group is converted to hydroxyl functionality in the final polymerproduct.

Also described are compositions comprising the polymers.

In preferred embodiments, these polymers and compositions thereof areused in oilfield applications, such as an inhibitor of gas hydrates. Thepolymer can assume alternating, block, and/or random configurations ofthe repeating units, with at least one ester group.

DESCRIPTION OF THE PRIOR ART

The extraction and fluid transport of oil and natural gas present manychallenges. Of primary concern in this invention is the inhibition ofgas hydrate formation in the extraction pipeline. It is well known thatthe presence of water in the hydrocarbon-containing line can facilitatethe formation of gas hydrate crystals, which can block the conduitand/or compromise the integrity of the construction materials. Lowermolecular weight hydrocarbon gases such as methane, ethane, propane,butane, and isobutane are especially prone to the formation of gashydrates. Elevated pressures and low temperatures aide interactionsbetween the dissolved hydrocarbon(s) and water. Such process conditionsare frequently encountered, especially during deep sea and arcticdrilling, causing these molecules to nucleate, crystallize, and producegas hydrate crystals. The formation, persistence, and accumulation ofgas hydrates during drilling and transport operations to the processingfacility may result in large pressure drops and/or extensive cost anddowntime if they impede fluid transport.

Methods have been developed to address these problems, and can becategorized into four general areas: (1) water removal from thetransport line, (2) thermal approaches to maintain and/or create atemperature profile inside the transport line so that gas hydrateformation is unfavorable, and (3) thermodynamic chemical (antifreezecompounds) addition to lower the gas hydrate crystallizationtemperature. However, due to problems with these methods, such as theflammability/toxicity of methanol as a thermodynamic inhibitor and thehigh cost of insulation and dehydration, other methods have beendeveloped. One of the most notable advances has been the development ofkinetic hydrate inhibitors, low-dose chemicals that retard, delay,and/or slow the formation of gas hydrates.

The prior art discloses gas hydrate inhibitors, for which polymericcompositions have proved beneficial. Representative compositions includethose disclosed in the following U.S. Pat. Nos. 4,915,176; 5,420,370;5,432,292; 5,639,925; 5,723,524; 6,028,233; 6,093,863; 6,096,815;6,117,929; 6,451,891; and 6,451,892. Gas hydrate inhibitors based onvinyl amide chemistries have been especially useful. Patents disclosingvinyl amides compositions used for gas hydrate inhibition include: U.S.Pat. Nos. 5,432,292; 5,723,524; 5,874,660; 6,028,233; 6,096,815;6,117,929; 6,180,699; 6,194,622; 6,242,518; 6,281,274; 6,451,892; and6,544,932.

A report on kinetic inhibitors of gas hydrates is provided in “Kineticinhibition of natural gas hydrates in offshore drilling, production, andprocessing,” a report from the Colorado School of Mines to the U.S.Department of Energy, 1994, which is incorporated in its entirety byreference.

Several polymers containing vinyl amides and hydroxyl units are known inthe prior art, but not as gas hydrate inhibitors. For example, US patentapplication 2005/0176849 teaches polyvinylpyrrolidone-based polymers forink jet printing, wherein the polymer may optionally comprise monomerunits with —OH functional groups, e.g., poly(vinylpyrrolidone-co-vinylalcohol). In US patent application 2006/0074144 there is a descriptionof water-based printing ink comprising a copolymer of an unsaturatedcarboxylic acid as a first monomer, and a second monomer selected fromthe group that includes vinyl amide-based monomers. The use ofpoly(vinyl pyrrolidone-co-vinyl alcohol) in photoresist compositions isdisclosed in US patent application 2008/0248427. In the field ofpressure-sensitive adhesives, Japanese patent JP5263055-A disclosesacrylic copolymers obtained by copolymerizing monomers consisting of atleast one selected from alkyl(meth)acrylates of formula CH₂═CR₁COOR₂(where R₁ is H or methyl; and R₂ is C1-C12 alkyl) and 3%-10% of one ormore of monomers selected from N-vinyl-2-pyrrolidone, acryloylmorpholine, N-isopropylacrylamide, N-vinyl-2-caprolactam and diacetoneacrylamide.

Terpolymers of N-vinyl-2-caprolactam, dimethylaminopropyl methacrylate,and hydroxyethylmethacrylate for use in coated substrates are providedin U.S. Pat. No. 7,402,641.

Additionally, Boyko (2004) discloses hydrogels ofN-vinyl-2-caprolactam-hydroxyethylmethacrylate produced by the radicalcrosslinking polymerization of the two monomers.

While advances in gas hydrate inhibition have been made, there yetremains a need for advanced polymer systems, especially those polymersthat offer enhanced functionality, such as molecular interaction. Thecompositions of the current invention surprisingly provide these desiredproperties.

SUMMARY OF THE INVENTION

The invention relates to polymers derived at least: (A) one N-vinylamide unit, and (B) one hydroxyl-containing acrylate unit, and topolymers derived at least from: (A) N-vinyl-2-caprolactam, and (B) oneunit having: (i) at least one hydroxyl group, and/or (ii) at least onefunctional group convertible to a hydroxyl group wherein at least onegroup is converted to hydroxyl functionality in the final polymerproduct.

In preferred embodiments, these polymers and compositions thereof areused in oilfield applications, such as an inhibitor of gas hydratesand/or a kinetic inhibitor of gas hydrates. The polymer can assumealternating, block, and/or random configurations of the repeating units,with at least one ester group.

LIST OF FIGURES

FIG. 1 is a graph of percent biodegradation for poly(70% VCAP-co-30%VOH) measured in accordance with Example 15.

FIG. 2 is a graph of percent biodegradation for poly(66% VCAP-co-34%VOH) measured in accordance with Example 16.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Disclosed herein are three classes of related polymers, which can begenerically describing as being derived from at least one N-vinyl amideunit, and a second unit having hydroxyl functionality. As described indetail later on, multiple methods exist for synthesizing the polymers.In particular, there is considerable flexibility with regard to thesecond unit, as the —OH group may exist prior to polymerization, or maybe obtained after polymerization from groups that can be converted tohydroxyl functionality.

The polymers of this invention may be synthesized with or withoutsolvent, wherein the reaction system may comprise any number of solventssuitable for conducting the reactions. Optionally, but not necessary,the reaction solvent may be replaced during and/or after the reactivesteps, and replaced by a different solvent. When the synthesizedpolymers are employed in the field of use, the delivery solvent systemmay comprise one or more of the reaction solvents, or the reactionsolvent system may be replaced entirely by a delivery solvent.

In preferred embodiments, the polymers exhibit degradability, which isexpected to enhance their usefulness in marine and/or soil environments.

In highly preferred embodiment, the polymers find utility in oilfieldapplications where they may function as anti-agglomerants, emulsifiers,de-emulsifiers, gas hydrate inhibitors, swelling inhibitors, and/orscale inhibitors. In especially preferred embodiments, the polymers andcompositions thereof are used as inhibitors of gas hydrates.

All percentages, ratio, and proportional used herein are based on aweight basis unless other specified.

The term gas hydrate inhibitor refers to polymers and compositionsthereof that prevent or retard the formation of gas hydrates, or reducethe tendency for said hydrates to agglomerate during storage and/orhydraulic transport of hydrocarbon-based fluids comprising water.

The term halide refers to chloro, bromo, iodo and fluoro, and ispreferably bromo or chloro.

The term monomer refers to the repeat units that comprise a polymer. Amonomer is a compound that chemically bonds to other molecules,including other monomers, to form a polymer.

The term homopolymer refers to a molecule that comprises a singlemonomer, and includes such polymers wherein a small amount ofpolymerization solvent may be covalently bonded into the polymer.

The term polymer refers to a molecule that comprises two or moredifferent monomers connected by covalent chemical bonds. By thisdefinition polymer encompasses molecules wherein the number of monomerunits ranges from very few, which more commonly may be called oligomers,to very many. Nonlimiting examples of polymers include copolymers,terpolymers, tetramers, and the like, wherein the polymer is a random,blocked, or alternating polymer.

The term copolymer refers to a polymer that comprises two differentmonomer units.

The term terpolymer refers to a polymer that comprises three differentmonomer units.

The term branched refers to any non-linear molecular structure. To avoidany arbitrary delineation, the term branched describes both branched andhyperbranched structures.

The term free radical addition polymerization initiator refers to acompound used in a catalytic amount to initiate a free radical additionpolymerization. The choice of initiator depends mainly upon itssolubility and its decomposition temperature.

The term inert solvent refers to a solvent that does not interferechemically with the reaction.

The term soil broadly refers to materials of varying composition thattypically contain various mineral constituents, weathered rock material,decomposed organic matter (humus), non-decomposed organic materials(e.g., leaves), and animal/insect material (e.g., dropping, casings).Soil means both synthetic and naturally occurring material of thisdescription.

The term personal care composition refers to compositions intended foruse on or in the human body, such as skin, sun, oil, hair, cosmetic, andpreservative compositions, including those to alter the color andappearance of the skin and hair. Potential personal care compositionsinclude, but are not limited to, compositions for increased flexibilityin styling, durable styling, increased humidity resistance for hair,skin, and color cosmetics, sun care water-proof/resistance,wear-resistance, and thermal protecting/enhancing compositions.

The term performance chemicals composition refers to non-personal carecompositions that serve a broad variety of applications, and includenonlimiting compositions such as: adhesives; agricultural, biocides,coatings, electronics, household-industrial-institutional (HI&I), inks,membranes, metal fluids, oilfield, paper, paints, plastics, printing,plasters, and wood-care compositions.

The subscripts m, n, and p as used herein with regard to chemicalstructures refer to integers commonly used in polymers to denote thenumber of repeating units of each monomer. In general, m, n, and p inthe present invention are independently selected such that the polymermolecular weight is from about 500 atomic mass units (amu) and 5,000,000amu.

First Embodiment of the Invention

By a first embodiment of the invention, polymers are provided beingderived at least from: (A) one N-vinyl amide unit, and (B) onehydroxyl-containing acrylate unit selected from the group consisting of:polyethylene glycol acrylate, polyethylene glycol methacrylate,2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate, 3-hydroxypropylacrylate, and blends thereof.

N-Vinyl Amide-Based Unit

The polymers described by this invention are derived in part from (A) atleast one N-vinyl amide-based unit. Both acyclic and cyclic constructsof these units are contemplated, which may be presented in the polymerin any type of arrangement, including, but not limited to: alternating,block, branched, linear, periodic, and/or random arrangements.

Cyclic N-vinyl amides, also known as N-vinyl lactams, may be used,either alone or in combination with acyclic N-vinyl amides. In preferredembodiments, the cyclic N-vinyl amide contain from 4 to 13 total carbonatoms.

Examples of cyclic vinyl amides include, but are not limited to:N-vinyl-2-pyrrolidone; N-vinyl piperidone; N-vinyl-2-caprolactam;N-vinyl-3-methylpyrrolidone; N-vinyl-4-methyl pyrrolidone;N-vinyl-5-methylpyrrolidone; N-vinyl-3-ethyl pyrrolidone;N-vinyl-3-butyl pyrrolidone; N-vinyl-3,3-dimethylpyrrolidone;N-vinyl-4,5-dimethylpyrrolidone; N-vinyl-5,5-dimethylpyrrolidone;N-vinyl-3,3,5-trimethylpyrrolidone; N-vinyl-5-methyl-5-ethylpyrrolidone; N-vinyl-3,4,5-trimethyl-3-ethyl pyrrolidone;N-vinyl-6-methyl-2-piperidone; N-vinyl-6-ethyl-2-piperidone;N-vinyl-3,5-dimethyl-2-piperidone; N-vinyl-4,4-dimethyl-2-piperidone;N-vinyl-6-propyl-2-piperidone; N-vinyl-3-octyl piperidone;N-vinyl-3-methyl-2-caprolactam; N-vinyl-4-methyl-2-caprolactam;N-vinyl-7-methyl-2-caprolactam; N-vinyl-3,5-dimethyl-2-caprolactam;N-vinyl-3,7-dimethyl-2-caprolactam; N-vinyl-4,6-dimethyl-2-caprolactam,N-vinyl-3,5,7-trimethyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam;N-vinyl-4-isopropyl-2-caprolactam; N-vinyl-5-isopropyl-2-caprolactam;N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-butyl-2-caprolactam;N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-tert-butyl-2-caprolactam;N-vinyl-2-methyl-4-isopropyl-2-caprolactam;N-vinyl-5-isopropyl-7-methyl-2-caprolactam;N-vinyl-4-octyl-2-caprolactam; N-vinyl-5-tert-octyl-2-caprolactam;N-vinyl-4-nonyl-2-caprolactam; N-vinyl-5-tert-nonyl-2-caprolactam; andblends thereof.

Due to their wide availability and known performance in gas hydrateinhibitor applications, N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactamare examples of preferred N-vinyl amides of the invention.

Hydroxyl-Containing Acrylate Unit

Novel polymers of the invention include those that also comprise atleast one hydroxyl-containing acrylate unit selected from the groupconsisting of: polyethylene glycol acrylate, polyethylene glycolmethacrylate, 2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate,3-hydroxypropyl acrylate, and blends thereof.

By way of example illustrated later, one such preferred polymer of theinvention is poly(N-vinyl-2-caprolactam-co-polyethylene glycolmethacrylate). It is possible to one skilled in polymerization scienceto produce the other polymers of the invention. By analogy to Example 1,poly(N-vinyl-2-caprolactam-co-2-hydroxyethyl acrylate) polymer can besynthesized as:

as can poly(N-vinyl-2-caprolactam-co-3-hydroxypropyl methacrylate)polymer:

Second Embodiment of the Invention

By a second embodiment of the invention, polymers are provided beingderived at least from two different units: (A) N-vinyl-2-caprolactam orits derivatives, and (B) one non-acrylate unit comprising:

-   -   (i) at least one hydroxyl group, and/or    -   (ii) at least one functional group convertible to a hydroxyl        group wherein at least one group is converted to hydroxyl        functionality in the final polymer product.

The term “N-vinyl-2-caprolactam and its derivatives” refers to the classof molecules based on N-vinyl-2-caprolactam having the structure:

wherein R is independently selected from the group consisting ofhydrogen, and functionalized and unfunctionalized alkyl, cycloalkyl,alkenyl, and aryl groups, wherein any of the beforementioned groups maybe with or without heteroatoms. Specific examples ofN-vinyl-2-caprolactam derivatives include, but are not limited to:N-vinyl-3-methyl-2-caprolactam; N-vinyl-4-methyl-2-caprolactam;N-vinyl-7-methyl-2-caprolactam; N-vinyl-3,5-dimethyl-2-caprolactam;N-vinyl-3,7-dimethyl-2-caprolactam; N-vinyl-4,6-dimethyl-2-caprolactam,N-vinyl-3,5,7-trimethyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam;N-vinyl-4-isopropyl-2-caprolactam; N-vinyl-5-isopropyl-2-caprolactam;N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-butyl-2-caprolactam;N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-tert-butyl-2-caprolactam;N-vinyl-2-methyl-4-isopropyl-2-caprolactam;N-vinyl-5-isopropyl-7-methyl-2-caprolactam;N-vinyl-4-octyl-2-caprolactam; N-vinyl-5-tert-octyl-2-caprolactam;N-vinyl-4-nonyl-2-caprolactam; and N-vinyl-5-tert-nonyl-2-caprolactam.

The non-acrylate unit, (B), is selected from the group of units thatalready have at least one hydroxyl group, or have at least one groupthat can be chemically converted to have hydroxyl functionality. Thefirst method includes ω-hydroxy alkenes, which have the generalstructure:

wherein n is an integer of 1 or more. Specific examples of ω-hydroxyalkenes include allyl alcohol and 3-buten-1-ol.

Also included in this category of non-acrylates units having at leastone hydroxyl group is the family of vinyl phenols, e.g., 2-vinyl phenol,3-vinyl phenol, and 4-vinyl phenol.

Alternatively, the (B) unit can be provided by at least one convertiblegroup has been converted to hydroxyl functionality in the final polymerproduct. In one embodiment of the invention, (B) is a polymerizableunit, and there are multiple reaction methods that are available to thepolymer chemist to incorporate the at least one hydroxyl-containing unitinto the polymer. Many examples of such polymerizable units are known,and include those based on the following chemistries: allyl, cinnamyl,fumaryl, (meth)acryl, stryenyl, and vinyl. Other families ofpolymerizable units can be identified by those skilled in the art.Favorable rates of reaction and product yields make this methodpreferred to the first. Many reactions of this category are known to oneskilled in the art, and include, without limitation:

-   -   (1) hydrolysis of vinyl acetates,    -   (2) alcoholysis of vinyl acetates,    -   (3) hydrolysis of vinyl esters,    -   (4) alcoholysis of vinyl esters,    -   (5) aminolysis of vinyl esters,    -   (6) hydrolysis of alkenyl halides,    -   (7) reduction of vinyl carboxylic acids, vinyl ketones and vinyl        aldehydes, and    -   (8) ring opening and nucleophilic addition of epoxides.

It is outside the scope of this invention to list every method by whicha hydroxyl group can be provided subsequent to polymerization. Instead,the above methods are meant to represent several techniques, andemphasize the diversity of chemistries that achieve the result. Adescription of these chemistries and reactions can be found in a text onorganic chemistry, such as Organic Chemistry by Morrison and Boyd(Prentice-Hall International, 1992), which is incorporated herein in itsentirety by reference.

In examples of the above categories (1)-(5), the polymerizable unitcomprises vinyl acetates, vinyl esters and/or alkenyl halides that arehydrolyzed, alcoholyzed, or aminolyzed to yield at least one hydroxylgroup. Vinyl acetate-based units are preferred, and examples of whichinclude, without limitation: vinyl acetate, methyl vinyl acetate, ethylvinyl acetate, and (pent-2-en-3-yl)acetate. Examples of vinyl estersinclude: 2-acetoxy-2-butene, 2-acetoxy-3-methyl-2-butene, isopropenylacetate, vinyl hexanoate, vinyl octanoate, vinyl propionate, vinyln-valerate, and blends thereof.

Examples of alkenyl halides include, without limitation:1-chloro-1-butene; 1-chloro-2-butene; 3-chlorocrotonic acid;3-chloro-methacrylic acid; 1-chloro-2-pentene; 2-chloro-2-butene;2-chloro-3-methyl-butene; 2-chloro-3-hexene; 2-chloro-2-pentene;4-chloro-prop-3-en-2-one; 1,2-dichloroethylene; trichloroethylene; vinylchloride; and vinylidene chloride, and their bromine and iodineanalogues, and blends thereof.

All ranges of hydrolysis, alcoholysis, and aminolysis are contemplated,meaning the conversion from ester and/or halide group to hydroxyl groupvaries from the smallest effective level (typically about 0.1%conversion) to 100% conversion.

Preferred embodiments of the invention synthesize the at least onehydroxyl group through the polymerization of vinyl acetate followed byhydrolysis or alcoholysis. Examples of this synthesis method areprovided in the Examples section.

In category (7), the hydroxyl group may be synthesized by polymerizationand subsequent reduction of vinyl carboxylic acids, vinyl ketones, andvinyl aldehydes.

A carboxylic acid functional group can be reduced an alcohol through areducing agent (e.g., lithium tetrahydridoaluminate). However, becauselithium tetrahydridoaluminate may react violently with water, it may bepreferred to perform the reduction anhydrously. In such cases, thedesired hydroxyl group is created by final treatment with acid, e.g.,dilute sulfuric acid. Examples of vinyl carboxylic acids include, butare not limited to: acrylic acid; 2-butenoic acid; cinnamic acid;2,3-dimethylacrylic acid; 3,3-dimethylacrylic acid;2,3-dimethyl-2-butenoic acid; 2-ethylacrylic acid; 2-ethyl-2-butenoicacid; fumaric acid; methacrylic acid, 2-pentenoic acid, 4-pentenoicacid, and blends thereof.

Likewise, a ketone functional group can be reduced to hydroxylfunctionality through a Grignard reaction followed by reaction withwater. Alternatively, the ketone functional group is reacted with areducing reagent (e.g., lithium tetrahydridoaluminate) as describedabove for carboxylic acid conversion. Examples of vinyl ketones include,but are not limited to: ethyl vinyl ketone; 2-hepten-4-one;hex-3-ene-2-one; 4-hexen-3-one; 3-methyl-3-penten-2-one;4-methyl-3-penten-2-one; 5-methyl-1-hexen-3-one; methyl vinyl ketone;3-penten-2-one; propyl vinyl ketone; and blends thereof.

The reactive methods described for vinyl ketones also can be employedfor converting aldehydes to hydroxyl functionality. Examples of vinylaldehydes that can be polymerized include, but are not limited to:but-2-enal; 2-butenedial; 3-butyn-1-al; cinnamic aldehyde;2-methyl-2-butenal; 2-methylene butyraldehyde; 2-methyl-2-pentenal;2-methyl-2-propenal; 3-methylbut-2-enal; 2-pentenedial; prop-2-enal, andblends thereof.

By category (8), the hydroxyl group of the polymer may be derived inpart through epoxide ring opening and addition by either acid- orbase-catalyzed nucleophilic addition/hydrolysis/reduction. Examples ofepoxides include, but are not limited to: 1,2-epoxybutane;2,3-epoxybutane; ethylene oxide; propylene oxide; isobutylene oxide; andblends thereof.

As an alternative to incorporating at least one hydroxyl group into thepolymer through a polymerizable unit, the hydroxyl group also may beintegrated into the polymer via one or more solvent adducts. Withoutattempting to exhaust the list of potential techniques, the at least onehydroxyl group may be incorporated into the polymer via a solvent adductduring the polymerization reaction(s). It is preferred that by thismethod, the reaction solvent comprise a hydroxyl group. Thus, suitablereaction solvents for use by this method include, but are not limitedto: alcohols (e.g., 1-butanol, 2-butanol, ethanol, ethylene glycol,methanol, 1-propanol, 2-propanol, and propylene glycol), and glycolethers (e.g., 2-methoxyethanol, 2-butoxyethanol, 2-isopropoxyethanol).Less preferably, the solvent adduct comprises a functionality that isconverted to the hydroxyl group, e.g., as described above for acetate,aldehyde, carboxylic acid, and ketone functional groups.

The number and arrangements of all of the polymerizable units in thepolymer are not restricted, as they may exist in alternating, block,branched, linear, periodic, and/or random arrangements, or occupyterminal positions.

Third Embodiment of the Invention

In addition to the two polymers described earlier, the present inventionalso provides a third embodiment for oilfield polymers being derived atleast from: (A) one N-vinyl amide; and (B) one unit comprising:

-   -   (i) at least one hydroxyl group, and/or    -   (ii) at least one functional group convertible to a hydroxyl        group wherein at least one group is converted to hydroxyl        functionality in the final polymer product.        This definition describes, in part, the polymers of the first        and second embodiments of the invention as oilfield polymers.

N-Vinyl Amide Unit

To avoid unnecessary repetition, the definition of the first unit, (A)one N-vinyl amide is the same as given in the first embodiment, andincludes the same non-limiting examples and preferred first units.

Unit Comprising at Least One Hydroxyl Group, and/or at Least OneFunctional Group Convertible to a Hydroxyl Group

The oilfield polymers of the invention also are derived, in part, fromat least one unit comprising:

-   -   (i) at least one hydroxyl group, and/or    -   (ii) at least one functional group convertible to a hydroxyl        group wherein at least one group is converted to hydroxyl        functionality in the final polymer product.

For this third embodiment, the (B) unit includes the definitionsdescribed for both the first and second embodiments of the invention.That is to say, that the (B) unit can comprise at least one hydroxylgroup that exists prior to the polymerization. Examples of suitablepolymerizable units within this category include, but are not limitedto: hydroxyl-containing acrylates (e.g., polyethylene glycol acrylate,polyethylene glycol methacrylate, 2-hydroxyethyl acrylate, hydroxyethylmethacrylate, 3-hydroxypropyl methacrylate, and 3-hydroxypropylacrylate), and ω-hydroxy alkenes (e.g., allyl alcohol and 3-buten-1-ol).All molecular weights of such units are contemplated. However, this isbut one method to impart the necessary hydroxyl group into the polymer.

By a second method, the polymerizable unit comprises at least onefunctional group that can be converted to a hydroxyl group, e.g., bychemical reaction. Again, to avoid unnecessary repetition, these typesof (B) units are described fully in the second embodiment of theinvention.

Alternatively, (B) may be incorporated into the polymer via one or moresolvent adducts. Without attempting to exhaust the list of potentialtechniques, the at least one hydroxyl group may be incorporated into thepolymer via a solvent adduct during the polymerization reaction(s). Itis preferred that by this method, the reaction solvent comprise ahydroxyl group. Thus, suitable reaction solvents for use by this methodinclude, but are not limited to: alcohols (e.g., 1-butanol, 2-butanol,ethanol, ethylene glycol, methanol, 1-propanol, 2-propanol, andpropylene glycol), and glycol ethers (e.g., 2-methoxyethanol,2-butoxyethanol, 2-isopropoxyethanol). Less preferably, the solventadduct comprises a functionality that is converted to the hydroxylgroup, e.g., as described above for acetate, aldehyde, carboxylic acid,and ketone functional groups.

The number and arrangements of all of the polymerizable units in thepolymer are not restricted, as they may exist in alternating, block,branched, linear, periodic, and/or random arrangements, or occupyterminal positions.

Broadly speaking, the nature of the unit comprising the hydroxyl groupmay contribute to the degradability of the invented compositions. Oneexample of a degradable hydroxyl-containing unit is a vinylalcohol-based unit, sc., produced by the hydrolysis or alcoholysis ofvinyl ester-based units. It is be noted, however, that degradability isnot a requirement of the hydroxyl-containing unit.

Reaction Solvent

The reactions of this invention can be performed with and without in areaction solvent. If a solvent is desired, both water-soluble andwater-insoluble reaction solvents may be used, and may be selected basedon a number of considerations, such as, but not limited to the finalproduct application. It is even possible to produce the polymer inmultiple steps, wherein one type of solvent is used in one step, thatsolvent removed, and then replace with a different type of solvent.

The system used to deliver the polymer composition may comprise areaction solvent, a blend of reaction solvents, or the reactionsolvent(s) may be removed and a different solvent system used forfurther reaction and/or delivery.

Examples of reaction solvents include, but are not limited to:

-   -   (A) water,    -   (B) straight-chain, branched, or cyclic alcohols (e.g.,        n-butanol, tert-butanol, ethanol, methanol, 1-propanol,        2-propanol),    -   (B) straight-chain, branched, or cyclic difunctional,        trifunctional or polyfunctional alcohols (e.g., ethylene glycol,        monoethylene glycol, glycerol propylene, glycol),    -   (C) homologues of ethylene oxide and propylene oxide units        (e.g., diethylene glycol, triethylene glycol),    -   (D) glycol ethers (e.g., 2-butoxyethanol, 2-ethoxyethanol,        2-isopropoxyethanol, 2-methoxyethanol, and 2-propoxyethanol)    -   (E) straight-chain, branched, or cyclic alkanes (e.g.,        cyclohexane, isooctane, n-hexane, n-heptane),    -   (F) alkylbenzenes (e.g., benzene, ethylbenzene, toluene,        xylene),    -   (G) monofunctional and difunctional (alkyl)benzenes (e.g.,        cresol, phenol, resorcinol),    -   (H) straight-chain, branched or cyclic aliphatic and aromatic        ketones (e.g., acetone, acetophenone, cyclohexanone, methyl        ethyl ketone),    -   (I) water-soluble organic solvents (e.g., alcohols,        dimethylformamide, dimethylacetamide, N-methylpyrrolidone,        N-ethylpyrrolidone, dimethyl sulfoxide, furan, tetrahydrofuran),    -   (J) water-insoluble organic solvent (e.g., alkylbenzenes,        straight-chain hydrocarbons, chlorinated hydrocarbons),    -   (K) natural or synthetic waxes, oils, fats, and emulsifiers        which are liquid under the polymerization conditions, both per        se and in a mixture with the abovementioned organic solvents or        with water.

The described polymers find use in oilfield applications, for example,as an inhibitor of gas hydrates. Thus, the composition may present thepolymer in a water-dispersible and/or water-soluble solvents. Withoutbeing bound to specific theory, it is believed that water-dispersibleand/or water-soluble solvents help to improve the effectiveness of thepolymer by promoting a greater extension of polymer molecule insolution. In addition, such solvents may help to improve the solubilityof the polymer in aqueous solution, and improve the compatibility of thecomposition at high injection temperature.

Examples of preferred water-dispersible and/or water-soluble reactionsolvents include, but are not limited to: alcohols, lactams(N-methylpyrrolidone), glycol ethers (e.g., 2-butoxyethanol,2-ethoxyethanol, 2-isopropoxyethanol, 2-methoxyethanol, and2-propoxyethanol), furans (e.g., furan, tetrahydrofuran), and blendsthereof.

Highly preferred reactions and/or delivery solvents are ethanol and2-propanol when the polymer is employed for gas hydrate inhibition.

An exemplary glycol ether is 2-butoxyethanol, which is highly preferredas a reaction solvent and/or delivery solvent.

In non-water based oilfield applications, there may be a preference forwater insoluble reaction solvent(s) and/or delivery solvent(s). Solventsthat are water insoluble include, but are not limited to: purehydrocarbons, meaning those compounds consisting entirely of only carbonand hydrogen (e.g., benzene, cyclohexane, heptane, hexane, octane,toluene, and xylene), and impure hydrocarbons, meaning those compoundsconsisting of carbon, hydrogen, and other bonded atoms (e.g.,chloroform, and dichloromethane).

In one embodiment of the invention, the reaction solvent also isemployed for delivery. Less preferably, the polymer is produced in onesolvent, that solvent removed, and then a preferred solvent or blends ofpreferred solvents added.

It is recognized that during the polymerization step (described below),an amount of the reaction solvent may be bonded covalently into theproduct, viz., incorporated into the polymer as a solvent adduct. Such asolvent adduct is possible with the described water-soluble reactionsolvents. The existence of such an adduct can be provided by ¹³C NMRstudies.

Again not to be bounded by theory, it is also believed that the solventadduct may impart surfactant-like properties to cause an extendedpolymer conformation in solution, which presumably exposes more of thepolymer molecule to interact with the hydrate crystal lattice.

Polymerization

Methods to produce the polymers are known to one skilled in the art, andinclude free radical polymerization, emulsion polymerization, ionicchain polymerization, and precipitation polymerization, the methods ofwhich are known to one skilled in the art. Free radical polymerizationis a preferred polymerization method, especially when usingwater-dispersible and/or water-soluble reaction solvent(s), and isdescribed in “Decomposition Rate of Organic Free Radical Polymerization”by K. W. Dixon (section II in Polymer Handbook volume 1, 4th edition,Wiley-Interscience, 1999), which is incorporated by reference.

Compounds capable of initiating the free-radical polymerization includethose materials known to function in the prescribed manner, and includethe peroxo and azo classes of materials. Exemplary peroxo and azocompounds include, but are not limited to: acetyl peroxide; azobis-(2-amidinopropane) dihydrochloride; azo bis-isobutyronitrile;2,2′-azo bis-(2-methylbutyronitrile); benzoyl peroxide; di-tert-amylperoxide; di-tert-butyl diperphthalate; butyl peroctoate; tert-butyldicumyl peroxide; tert-butyl hydroperoxide; tert-butyl perbenzoate;tert-butyl permaleate; tert-butyl perisobutylrate; tert-butylperacetate; tert-butyl perpivalate; para-chlorobenzoyl peroxide; cumenehydroperoxide; diacetyl peroxide; dibenzoyl peroxide; dicumyl peroxide;didecanoyl peroxide; dilauroyl peroxide; diisopropyl peroxodicarbamate;dioctanoyl peroxide; lauroyl peroxide; octanoyl peroxide; succinylperoxide; and bis-(ortho-toluoyl) peroxide.

Also suitable to initiate the free-radical polymerization are initiatormixtures or redox initiator systems, including: ascorbic acid/iron (II)sulfate/sodium peroxodisulfate, tert-butyl hydroperoxide/sodiumdisulfite, and tert-butyl hydroperoxide/sodium hydroxymethanesulfinate.

The polymer can be synthesized using a one-step technique. A one-stepmethod may facilitate production, as the reactants (including initiator)can be charged into the reaction vessel in one campaign. To maintain theelegance of this one-step technique, it is preferred to polymerize atleast one unit that already comprises a hydroxyl group, and therebyavoid a separate conversion reaction step. By non-limiting example ofthis method, N-vinyl amide and hydroxyethyl methacrylate can be chargedinto a reactor with 2-butoxyethanol and tert-amylperoxy-2-ethylhexanoate to synthesize poly(N-vinyl amide-co-hydroxyethylmethacrylate).

Alternatively, the described polymer is produced in two steps. The firststep is a polymerization comprising at least one N-vinyl amide-basedunit, and at least one polymerizable unit comprising at least one groupconvertible to a hydroxyl group. The second step is the conversion ofsome or all of the convertible functional groups to hydroxylfunctionality. Example 3 illustrates a two-step method.

Composition and Use Levels

Polymers produced by this invention comprise, by weight:

-   -   from about 1% to about 99% of N-vinyl-2-caprolactam (Embodiment        1), or an N-vinyl amide unit (Embodiments 2 and 3), and    -   from about 1% to about 99% of a hydroxyl-containing acrylate        unit (Embodiment 1), or a non-acrylate unit comprising a        hydroxyl group, and/or a unit comprising a functional group        convertible to hydroxyl functionality (Embodiment 2), or a unit        comprising a hydroxyl group, and/or a unit comprising a        functional group convertible to hydroxyl functionality        (Embodiment 3).

More preferably, the polymers comprise:

-   -   from about 50% to about 99% of N-vinyl-2-caprolactam (Embodiment        1), or an N-vinyl amide unit (Embodiments 2 and 3), and    -   from about 1% to about 50% of a hydroxyl-containing acrylate        unit (Embodiment 1), or a non-acrylate unit comprising a        hydroxyl group, and/or a unit comprising a functional group        convertible to hydroxyl functionality (Embodiment 2), or a unit        comprising a hydroxyl group, and/or a unit comprising a        functional group convertible to hydroxyl functionality        (Embodiment 3).

In especially preferred embodiments, the polymers produced by thisinvention comprise:

-   -   from about 60% to about 99% of N-vinyl-2-caprolactam (Embodiment        1), or an N-vinyl amide unit (Embodiments 2 and 3), and    -   from about 1% to about 40% of a hydroxyl-containing acrylate        unit (Embodiment 1), or a non-acrylate unit comprising a        hydroxyl group, and/or a unit comprising a functional group        convertible to hydroxyl functionality (Embodiment 2), or a unit        comprising a hydroxyl group, and/or a unit comprising a        functional group convertible to hydroxyl functionality        (Embodiment 3).

The aforementioned polymer compositions have a molecular weight of about500 amu to about 5,000,000 atomic mass units (amu), as determined by gelpermeation chromatography using polyethylene glycol standards. Morepreferably, the polymer molecular weight is from about 500 amu to about100,000 amu.

When the polymers are employed as gas hydrate inhibitors, then anyconvenient concentration of inhibitor in the delivery solvent can beused, so long as it is effective in its purpose. Generally, thepolymeric gas hydrate inhibitor is used in an amount of about 0.1% toabout 3% by weight of the water present. The compositions also mayinclude (without limitation) one or more biocides, corrosion inhibitors,emulsifiers, de-emulsifiers, water-soluble salts having a multivalentcation, defoamers, lubricants, rheology modifiers, and/or shale swellinginhibitor. These adjuvants and their addition levels are known to oneskilled in the art of Oilfield applications, especially gas hydrateformulations.

The water-soluble metal salt comprising multivalent cations is suitablya water-soluble salt of a metal from Group II or Group VI of the PeriodTable. More specifically, these are suitably salts of one or more metalsselected from copper, calcium, magnesium, zinc, aluminium, iron,titanium, zirconium and chromium. Since the salts must be water-soluble,they are preferably the halides, nitrates, formates and acetates ofthese metals. In choosing the relevant metal, care must be taken toensure that the conditions in the rock formation matrix are not such asto cause scaling by one of these metals. Calcium chloride, magnesiumchloride or mixtures thereof is preferred. The solution of the watersoluble salt is suitably an aqueous solution.

It is contemplated that higher concentrations may be preferred in someapplications. For example, at low application temperature high polymerconcentrations may be needed to effectively inhibit gas hydrateformation and/or conduit blockage. Other applications may benefit from areduced volume of concentrate solution, as it may simplify producthandling and/or ease introduction into the petroleum fluid. Nonetheless,it is understood that the actual concentration will vary, depending uponmany parameters like the specific application, selection of carriersolvent, the chemical composition of the inhibitor, the systemtemperature, and the inhibitor's solubility in the carrier solvent atapplication conditions. A suitable concentration for a particularapplication, however, can be determined by those skilled in the art bytaking into account the inhibitor's perfounance under such application,the degree of inhibition required for the petroleum fluid, and theinhibitor's cost.

Degradability

Quite unexpectedly, the discovery was made that polymers of theinvention also may exhibit degradability, meaning that the molecule isbroken down into one or more parts by biological, chemical, and/or othermechanisms. However, without being bound by theory, it is believed thatthe biological and/or chemical factors of the seawater test also may bepresent, or different factors may exist to provide polymer degradabilityin other environments, such as soil.

It is possible to engineer degradability into the polymers of thepresent invention with proper selection and ratios of the two prescribedunits of Embodiments 1, 2, and 3. Broadly speaking, the nature of theunit comprising the hydroxyl group may contribute to the degradabilityof the invented compositions. One example of a degradablehydroxyl-containing unit is a vinyl alcohol-based unit, sc., produced bythe hydrolysis or alcoholysis of vinyl ester-based units. Due to thecomplexity of all contributing factors, it is not possible to prescribepolymer composition-degradability results. For example, two examples ofthe invention are provided wherein greater degradability was attainedfrom the polymer having lower vinyl alcohol content (30% vs. 50%).

It is noted, however, that degradability is not a requirement for thepolymers of the invention.

Such polymers and compositions thereof may serve a variety of personalcare and performance chemicals compositions, especially wheredegradability is a desired feature. These fields include, withoutlimitation: adhesive, agriculture, cleaning, coating, dental,encapsulation, imaging, household/industrial/institutional, medical,membrane, oilfield, oral care, packaging, personal care, performancechemicals, pharmaceutical, printing, and veterinary applications.

In highly preferred embodiments, the polymers find application as gashydrate inhibitors for oilfield treatment.

Product Characterization

The final product can be analyzed by known techniques to characterizethe product. Especially preferred are the techniques of ¹³C nuclearmagnetic resonance (NMR) spectroscopy, gas chromatography (GC), and gelpermeation chromatography (GPC) in order to decipher polymer identity,residual monomer concentrations, polymer molecular weight, and polymermolecular weight distribution.

Nuclear magnetic resonance (NMR) spectroscopy is an especially preferredmethod to probe the polymerization product in terms of chemicalproperties such as monomeric composition, sequencing and tacticity.Analytical equipment suitable for these analyses include the Inova400-MR NMR System by Varian Inc. (Palo Alto, Calif.). References broadlydescribing NMR include: Yoder, C. H. and Schaeffer Jr., C. D.,Introduction to Multinuclear NMR, The Benjamin/Cummings PublishingCompany, Inc., 1987; and Silverstein, R. M., et al., SpectrometricIdentification of Organic Compounds, John Wiley & Sons, 1981, which areincorporated in their entirety by reference.

Residual monomer levels can be measured by GC, which can be used toindicate the extent of reactant conversion by the polymerizationprocess. GC analytical equipment to perform these tests are commerciallyavailable, and include the following units: Series 5880, 5890, and 6890GC-FID and GC-TCD by Agilent Technologies, Inc. (Santa Clara, Calif.).GC principles are described in Modern Practice of Gas Chromatography,third edition (John Wiley & Sons, 1995) by Robert L. Grob and Eugene F.Barry, which is hereby incorporated in its entirety by reference.

GPC is an analytical method that separates molecules based on theirhydrodynamic volume (or size) in solution of the mobile phase, such ashydroalcoholic solutions with surfactants. GPC is a preferred method formeasuring polymer molecular weight distributions. This technique can beperformed on known analytical equipment sold for this purpose, andinclude the TDAmax™ Elevated Temperature GPC System and the RImax™Conventional Calibration System by Viscotek™ Corp. (Houston, Tex.). Inaddition, GPC employs analytical standards as a reference, of which aplurality of narrow-distribution polyethylene glycol and polyethyleneoxide standards representing a wide range in molecular weight is thepreferred. These analytical standards are available for purchase fromRohm & Haas Company (Philadelphia, Pa.) and Varian Inc. (Palo Alto,Calif.). GPC is described in the following texts, which are herebyincorporated in their entirety by reference: Schroder, E., et al.,Polymer Characterization, Hanser Publishers, 1989; Billingham, N.C.,Molar Mass Measurements in Polymer Science, Halsted Press, 1979; andBillmeyer, F., Textbook of Polymer Science, Wiley Interscience, 1984.

The following, non-limiting examples are intended to illustrate theembodiments of the invention:

EXAMPLES Example 1 Synthesis of poly(95% VCAP-co-5% HEMA) in BGE withinitiator

Preparation of feed solution #1: N-vinyl-2-caprolactam (VCAP) (9.5 g)and hydroxyethyl methacrylate (HEMA) (0.5 g) were codissolved in2-butoxyethanol (BGE) (40 g).

Preparation of feed solution #2: N-vinyl-2-caprolactam (85.5 g) andhydroxyethyl methacrylate (4.5 g) were codissolved in 2-butoxyethanol(60 g).

Feed solution #1 was charged into the reaction kettle and heated to 116°C. under nitrogen purge. After reaching temperature, a tent-amylperoxy-2-ethylhexanoate initiator, Trigonox® 121 (0.375 g), was added,and the mixture was stirred for 15 minutes.

Over a period of 3 hours, feed solution #2 was pumped into the reactionkettle containing feed solution #1, and, simultaneously, 13 charges ofTrigonox® 121 (each 0.375 g) were added to the reactor every 15 minutes.

After the last charge of Trigonox® 121 the reaction kettle was cooled to105° C., at which point additional Trigonox® 121 (0.375 g) was addedinto the reaction kettle. Thirty minutes later, a final charge ofTrigonox® 121 (0.375 g) was added to the reaction kettle and thetemperature was held for 1 hour.

Thereafter, the reaction kettle was allowed to cool to room temperature,and a brown, viscous polymer was discharged from the reaction kettle.The molecular weight of the polymer was measured by GPC and found to bewithin the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 2 Synthesis of poly(95% VCAP-co-5% PEGMA) in BGE withoutInitiator

The method of Example 1 was employed with the following changes:

In feed solution #1, N-vinyl-2-caprolactam (9.5 g) and polyethyleneglycol methacrylate (PEGMA) (0.5 g) [with a weight-average molecularweight (M_(w)) of 526 amu] were codissolved in 2-butoxyethanol (40 g).

In feed solution #2, N-vinyl-2-caprolactam (85.5 g) and polyethyleneglycol methacrylate (PEGMA) (4.5 g), [with a M_(w) of 526 amu], werecodissolved in 2-butoxyethanol (60 g).

Upon cooling, a brown, viscous polymer was discharged from the reactionkettle. The molecular weight of the polymer was measured by GPC andfound to be within the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm, n and p may be any integer equal to or greater than 1.

Example 3 Synthesis of poly(82% VCAP-co-18% VOH) in MeOH/H₂O withInitiator

Synthesis of poly(70% VCAP-co-30% VAc)

Preparation of feed solution #1: N-vinyl-2-caprolactam (140 g), N-vinylacetate (VAc) (60 g), and methanol (MeOH) (50 g) were mixed in a beaker.

Preparation of feed solution #2: Trigonox® 121 (12 g) was dissolved inmethanol (50 g).

A 1-L stainless steel reactor was fitted with propeller agitator, refluxcondenser, nitrogen inlet tube and thermocouple reactor. Methanol (300g) was added, and then, under nitrogen purge, was heated to 116° C.

Then, all of the feed solution #1 and a portion of feed solution #2 (52g) were fed over 180 minutes. After 15 minutes, the remainder of feedsolution #2 was charged over 30 minutes.

After another one hour reaction, the reactor was cooled down to roomtemperature. The product obtained from the polymerization reaction was abrown, viscous copolymer of poly(VCAP-co-VAc) (70/30 mass ratio) inmethanol at 33% solids.

The poly(VCAP-co-VAc) copolymer had a M_(w) of 4,000, as determined bygel permeation chromatography (polyethylene glycol standard).

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Hydrolysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a thermowatch, thepoly(VCAP-co-VAc) product (i.e., polymer in reaction solvent) of thisexample (100 g) was mixed with a 20% sodium hydroxide (NaOH) solution(24.5 g).

The reactor was heated under nitrogen purge to 50° C.

After 4 hours of reaction, the reactor was cooled down to roomtemperature. The product discharged from the vessel and vacuumfiltrated. The filtrate obtained was a brown, viscous copolymer ofpoly[VCAP-co-vinyl alcohol (VOH)] (82/18 mass ratio) in a mixture ofmethanol and water (reaction product) (MeOH/H₂O=3:1), which wasconfirmed by FT-IR spectroscopy. The molecular weight of the polymer wasmeasured by GPC and found to be within the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 4 Synthesis of poly(82% VCAP-co-18% VOH) in MeOH/H₂O withInitiator

The polymerization procedure of Example 3 was followed.

Hydrolysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a thermowatch,charge NaOH (>97% pure) pellet (5.0 g) into the poly(VCAP-co-VAc)product (i.e., polymer in reaction solvent) of this example (100 g).

The reactor was heated under nitrogen purge to 50° C.

After 4 hours of reaction, the reactor was cooled down to roomtemperature. The product discharged from the vessel and vacuumfiltrated. The filtrate obtained was a brown, viscous copolymer ofpoly[VCAP-co-vinyl alcohol (VOH)] (82/18 mass ratio) in a mixture ofmethanol and water (reaction product) (MeOH/H₂O=3:1), which wasconfirmed by FT-IR spectroscopy. The molecular weight of the polymer wasmeasured by GPC and found to be within the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 5 Synthesis of poly(82% VCAP-co-18% VOH) in MeOH/H₂O

Synthesis of poly(70% VCAP-co-30% VAc)

Preparation of feed solution #1: N-vinyl-2-caprolactam (168 g), andN-vinyl acetate (72 g) were dissolved in methanol (50 g).

Preparation of feed solution #2: Luperox® 11 M75 (21.6 g), a tert-butylperoxypivalate initiator, was dissolved in methanol (50 g).

A 1-L stainless steel reactor was fitted with propeller agitator, refluxcondenser, nitrogen inlet tube and thermocouple reactor. Methanol (250g) was added, and then, under nitrogen purge, was heated to 80° C.

Then, all of feed solution #1 was feed into the reactor over 180 minuteswhile feeding solution #2 was feed into the reactor over 210 minutes.

The reaction was held for 2 hours and then the reactor was cooled downto room temperature. The product obtained from the polymerizationreaction was a brown, viscous copolymer of poly(VCAP-co-VAc) (70/30 massratio) in methanol at 40% solids.

The poly(VCAP-co-VAc) copolymer had a M_(w) of about 2,000 amu(polyethylene glycol standard).

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Hydrolysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a theimowatch, thepoly(VCAP-co-VAc) product (i.e., polymer in reaction solvent) of thisexample (200 g) was mixed with a 20% NaOH solution (50 g).

The reactor was heated under nitrogen purge to 50° C.

After 4 hours of reaction, the reactor was cooled down to roomtemperature. After vacuum filtration, the product obtained was a brown,viscous copolymer of poly(VCAP-co-VOH) (82/18 mass ratio) in a mixtureof methanol and water (reaction product) (MeOH/H₂O=2:1 mass ratio). Themolecular weight of the polymer was measured by GPC and found to bewithin the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 6 Synthesis of poly(82% VCAP-co-18% VOH) in BGE/H₂O

Synthesis of poly(70% VCAP-co-30% VAc)

Preparation of feed solution #1: N-vinyl-2-caprolactam (350 g), andN-vinyl acetate (150 g) were dissolved in BGE (450 g).

Preparation of feed solution #2: Luperox® 11 M75 (50.0 g), a tert-butylperoxypivalate initiator, was dissolved in BGE (50 g).

A 1-L stainless steel reactor was fitted with propeller agitator, refluxcondenser, nitrogen inlet tube and thermocouple reactor. BGE (150 g) wasadded, and then, under nitrogen purge, was heated to 80° C.

Then, all of the feed solution #1 and a portion of feed solution #2 (72g) were fed over 180 minutes. After 30 minutes, the remainder of feedsolution #2 was charged over 30 minutes.

The reaction was held for 1.5 hours. Then, the reactor was cooled downto room temperature. The product obtained from the polymerizationreaction was a brown, viscous copolymer of poly(VCAP-co-VAc) (70/30 massratio) in BGE at 43.5% solids.

The poly(VCAP-co-VAc) copolymer had a M_(y), of about 2,100 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Hydrolysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a thermowatch, thepoly(VCAP/VAc) product of this example (250 g) was mixed with a 30% NaOHsolution (50 g).

The reactor was heated under nitrogen purge to 50° C. and held for 4hours. Thereafter, the reactor was cooled down to room temperature andvacuum filtrated to remove the solids.

This obtained product was a brown, viscous copolymer ofpoly(VCA-co-/VOH) (82/18 mass ratio) at 40% solids in a mixture of BGEand water (reaction product) (BGE/H₂O=2.8/1.0 mass ratio). The molecularweight of the polymer was measured by GPC and found to be within therange of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 7 Synthesis of poly(82% VCAP-co-18% VOH) in BGE/H₂O

The polymerization procedure of Example 6 was followed.

Hydrolysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a thermowatch, thepoly(VCAPNAc) product of this example (450 g) was mixed with a 22% NaOHsolution (147 g). The reactor was heated under nitrogen purge to 50° C.and held for 5 hours. Thereafter, the reactor was cooled down to roomtemperature to discharge the products. Centrifuge the product and decantto remove the solids.

This obtained product was a brown, viscous copolymer ofpoly(VCA-co-/VOH) (82/18 mass ratio) at 40% solids in a mixture of BGEand water (reaction product) (BGE/H₂O=2.8/1.0 mass ratio). The molecularweight of the polymer was measured by GPC and found to be within therange of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 8 Synthesis of Poly(82% VCAP-co-18% VOH) in BGE/H₂O

Synthesis of poly(70% VCAP-co-30% VAc)

Preparation of feed solution #1: N-vinyl-2-caprolactam (210 g) andN-vinyl acetate (90 g) were codissolved in BGE.

Preparation of feed solution #2: Luperox® 11 M75 (30.0 g), a tert-butylperoxypivalate initiator, was dissolved in BGE (60 g).

A 1-L stainless steel reactor was fitted with propeller agitator, refluxcondenser, nitrogen inlet tube and thermocouple reactor. BGE (240 g) wasadded, and then, under nitrogen purge, was heated to 80° C.

Then, all of the feed solution #1 and a portion of feed solution #2 (72g) were fed over 210 minutes. After 30 minutes, the remainder of feedsolution #2 was fed into the reactor over 30 minutes.

The reaction was held for 1 hour. Then, the reactor was cooled down toroom temperature. The product obtained from the polymerization reactionwas a brown, viscous copolymer of poly(VCAP-co-VAc) (70/30 mass ratio)in BGE at 48.3% solids.

The poly(VCAP-co-VAc) copolymer had a M_(w) of about 2200 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Hydrolysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a thermowatch, thepoly(VCAP-co-VAc) product of this example (250 g) was mixed with a 21.5%NaOH solution (83.5 g).

The reactor was heated under nitrogen purge to 50° C. and held for 4hours. Thereafter, the reactor was cooled down to room temperature.

Then, 200 g of deionized water was added to the reactor and stirred for30 minutes. The product was transferred from the reactor to a senaratingfunnel and allowed to settle until the mixture was separated into twolayers. The bottom layer was removed, and the remaining top layer wasdistilled at 50° C. and 25 mm Hg. The product obtained afterdistillation was 40% solids.

The obtained product was a brown, viscous copolymer of poly(VCA-co-VOH)(82/18 mass ratio) in a mixture of BGE and water (reaction product). Themolecular weight of the polymer was measured by GPC and found to bewithin the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 9 Synthesis of poly(82% VCAP-co-18% VOH) in BGE/MeOH

The polymerization procedure of Example 8 was followed.

Alcoholysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a thermowatch, thepoly(VCAP-co-VAc) product of this example (100 g) was mixed with 25% ofsodium methoxide in methanol (2 g), and methanol (50 g). The reactionmixture was heated to 65° C. and then refluxed for 16 hours. Thereafterthe reaction was cooled to room temperature.

The final product was a clear, brown, viscous copolymer ofpoly(VCAP-co-VOH) (82/18 mass ratio) in BGE and methanol(BGE/methanol=1/1.16 mass ratio). The molecular weight of the polymerwas measured by GPC and found to be within the range of 2000 amu-4000amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 10 Synthesis of poly(82% VCAP-co-18% VOH) in BGE

The polymerization procedure of Example 8 was followed.

Alcoholysis to Produce poly(82% VCAP-co-18% VOH)

In a three neck flask equipped with a condenser and a thermowatch, thepoly(VCAP/VAc) product of this example (100 g) was mixed with 25% ofSodium Methoxide in Methanol (2 g), Na2CO3 ((2.0 g) and Methanol (50 g).The reaction mixture was heated to 65° C. and refluxed for 8 hours.Thereafter the reaction was cooled down to room temperature. Thenproduct was discharged, and filtrated to remove the solids.

The final product was a clear, brown, viscous copolymer ofpoly(VCAP-co-VOH) (82/18 mass ratio) in BGE and methanol(BGE/methanol=1/1.16 mass ratio). The molecular weight of the polymerwas measured by GPC and found to be within the range of 2000 amu-4000amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 11 Synthesis of poly(82% VCAP-co-18% VOH) in IPA/H₂O

Synthesis of poly(70% VCAP-co-30% VAc) in IPA

The polymerization procedure of Example 6 was followed except thesolvent was IPA.

The polymerization product was produced at 50% solids.

Hydrolysis to Produce poly(82% VCAP-co-18% VOH)

The hydrolysis procedure of Example 6 was followed with thepoly(VCAP-co-VAc) product of this example.

The final product obtained was a clear, brown and viscous copolymer ofpoly(VCAP-co-VOH) (82/18 weight ratio) in IPA and water. The molecularweight of the polymer was measured by GPC and found to be within therange of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 12 Synthesis of poly(74% VCAP-co-26% VOH) in BGE/H₂O

Synthesis of poly(60% VCAP-co-40% VAc) in BGE with initiator

The polymerization procedure of Example 6 was followed exceptN-vinyl-2-caprolactam and N-vinyl acetate (60/40 mass ratio) were codissolved in BGE.

The polymerization product was produced at 50±2% solids.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Hydrolysis to Produce poly(74% VCAP-co-26% VOH)

The hydrolysis procedure of Example 6 was followed with thepoly(VCAP-co-VAc) product of this example, except that a 33.33% NaOHsolution (54 g) was used.

The final product was a clear, brown, viscous copolymer ofpoly(VCAP-co-VOH) (74/26 mass ratio) in BGE and water. The molecularweight of the polymer was measured by GPC and found to be within therange of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 13 Synthesis of poly(66% VCAP-co-34% VOH) in BGE/

Synthesis of poly(50% VCAP-co-50% VAc) in BGE with Initiator

The polymerization procedure of Example 6 was followed exceptN-vinyl-2-caprolactam and N-vinyl acetate (50/50 mass ratio) were codissolved in the same reaction solvent.

The polymerization product was produced at 50±2% solids.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Hydrolysis to Produce poly(66% VCAP-co-34% VOH)

The hydrolysis procedure of Example 7 was followed with thepoly(VCAP-co-VAc) product of this example, except that a 33.3% NaOHsolution was used.

The final product was a clear, brown, viscous copolymer ofpoly(VCAP-co-VOH) (66/34 mass ratio) in a mixture of BGE and water(reaction product). The molecular weight of the polymer was measured byGPC and found to be within the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 14 Synthesis of poly(56% VCAP-co-44% VOH) in SGE/H₂O

Synthesis of poly(40% VCAP-co-60% VAc) in BGE

The polymerization procedure of Example 6 was followed exceptN-vinyl-2-caprolactam and N-vinyl acetate (40/60 mass ratio) weredissolved in BGE.

The polymerization product was produced at 50±2% solids.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Hydrolysis to Produce poly(56% VCAP-co-44% VOH)

The hydrolysis procedure of Example 7 was followed with thepoly(VCAP-co-VAc) product of this example.

The final product was a clear, brown, viscous copolymer ofpoly(VCAP-co-VOH) (56/44 mass ratio) in a mixture of BGE and water(reaction product). The molecular weight of the polymer was measured byGPC and found to be within the range of 2000 amu-4000 amu.

The polymer product can assume alternating, block, and/or randomconfigurations of the repeating units. The chemical structure subscriptsm and n may be any integer equal to or greater than 1.

Example 15 Biodegradability Testing of poly(82% VCAP-co-18% VOH) inBGE/H₂O

The hydrolyzed polymer synthesized in Example 7 was tested forbiodegradability in seawater using the OECD Guideline 306,“Biodegradability in Seawater, Closed Bottle Method,” which is herebyincorporated in its entirety by reference. The employed GLP methodmeasured the biodegradability of a sample in unpolluted,nutrient-enriched seawater. Biodegradability was calculated as the ratioof the measured biochemical oxygen demand (BOD) to the theoreticaloxygen demand (ThOD). The polymer of Example 7 was added to the testsystem at a concentration corresponding to 4.50 ThOD/L in the testsubstance solution. The reference substance (sodium benzoate) was addedto the test system at a concentration corresponding to 4.01 mg ThOD/L inthe reference substance solution.

Biodegradation was calculated based on measured values after 7, 14, 21,and 28 days (FIG. 1). The biodegradation of poly(70% VCAP-co-30% VOH)after 28 days was calculated to be 76%. OECD Guideline 306 provides anindication of biodegradation in seawater when the calculatedbiodegradation exceeds 60%, and poly(70% VCAP-co-30% VOH) is believed tobe degradable in a marine environment.

Example 16 Biodegradability Testing of poly(66% VCAP-co-34% VOH) inBGE/H₂O

The hydrolyzed polymer synthesized in Example 13 was tested forbiodegradability in seawater using the same method described in Example15.

Biodegradation was calculated based on measured values after 7, 14, 21,and 28 days (FIG. 2). The biodegradation of poly(66% VCAP-co-34% VOH)after 28 days was calculated to be 76%. OECD Guideline 306 provides anindication of biodegradation in seawater when the calculatedbiodegradation exceeds 60%, and poly(70% VCAP-co-30% VOH) is believed tobe degradable in a marine environment.

Method 1: Measurement of Kinetic Gas Hydrate Inhibition

The following steps were employed to measure the kinetic gas hydrateinhibition of polymerization products of this invention:

-   -   1. A 500 mL, 316 stainless steel autoclave vessel, equipped with        a thermostated cooling jacket, sapphire window, inlet and outlet        ports, platinum resistance thermometer (PRT), and a magnetic        stirring pellet was selected. The autoclave was rated for use        between −25° C. to 400° C. Temperature and pressure data were        recorded by a thermocouple and pressure transducer,        respectively, and recorded by computer data acquisition        software. The cell contents were visually monitored by a        baroscope video camera connected to a time lapsed video        recorder.    -   2. The rig was cleaned using prior to running blank or test        solutions:        -   a. An air drill with a wet emery-paper buffer head was used            to passivate the interior stainless steel surface wall of            the rig.        -   b. The vessel was then rinsed several times with double            distilled water and dried with lint-free tissue.    -   3. Approximately 200 g of gas hydrate inhibitor solution, made        in double-distilled water, were added to the rig to produce a        defined concentration (e.g., 0.5%, 0.6%, 0.75%). The rig top was        replaced and tightened.    -   4. The solution was stirred by a magnetic stirrer at 500 rpm.    -   5. Then, the autoclave was purged with an experimental        hydrocarbon test mixture (Green Canyon Gas) (Table 1) for 60        seconds.    -   6. The system was pressurized to a defined pressure (e.g., 35        bar, 60 bar) at room temperature.    -   7. After pressurization, the temperature was reduced from room        temperature to a defined chill temperature (e.g., 4° C., 7° C.)        (see step 11). The reactor pressure was maintained with Green        Canyon Gas as the solution temperature was reduced.    -   8. The pressure and temperature data logging devices were        activated.    -   9. The rig was maintained at the defined chill temperature and        pressure until gas hydrates were detected.    -   10. Hydrate formation in the rig was determined by any one of        three indicators: (1) visual detection of hydrate crystals        (i.e., non-clear solution), (2) a decrease in vessel pressure        due to gas uptake by the solution, or (3) an increase in        solution temperature created by the exothermic gas hydrate        reaction.    -   11. A commercial software package, pvtsim (Calsep AIS, Lyngby,        Denmark) was used to predict the Green Canyon Gas equilibrium        melting temperature. For test pressures of 35 bar and 60 bar,        the equilibrium melting temperatures are about 13.5° C. and        17.3° C., respectively. The kinetic gas hydrate inhibition tests        were conducted 35 bar and 4° C.; and 60 bar and 7° C. in order        to create subcooling temperatures (ΔT_(sc)) of 9.5° C. and 10.5°        C., respectively. (Subcooling temperature is the difference        between the equilibrium melting temperature and the experimental        fluid temperature.)    -   12. Gas hydrate inhibition efficiency is proportional to the        induction time, which is the time from the start of the run        (viz., step 8) to the time when gas hydrates are detected (viz.,        step 10).

TABLE 1 Composition of the experimental hydrocarbon gas mixturecomposition. component amount nitrogen 0.39 methane 87.26 ethane 7.57propane 3.10 iso-butane 0.49 N-butane 0.79 iso-pentane 0.20 N-pentane0.20 total 100.00

Examples 17-30 Gas Hydrate Inhibition Measurement

Method 1 was used to measure the gas hydrate inhibition for compositionsof this invention.

Excellent gas hydrate inhibition, with induction times in excess of2,800 minutes (48 hours), were achieved by compositions of thisinvention (Table 2).

TABLE 2 Gas hydrate inhibition results Active induction level ΔT_(sc)*time ex. sample composition solvent (%) (° C.) (min) 17 Example 1 95%VCAP-co-5% HEMA BGE 0.6 10.5 >2880 18 Example 1 95% VCAP-co-5% HEMA BGE0.5 9.5 >2880 19 Example 3 82% VCAP-co-18% VOH MeOH/H₂O 0.6 10.5 >288020 Example 4 82% VCAP-co-18% VOH MeOH/H₂O 0.6 10.5 >2880 21 Example 582% VCAP-co-18% VOH MeOH/H₂O 0.6 10.5 >2880 22 Example 6 82% VCAP-co-18%VOH BGE/H₂O 0.6 10.5 >2880 23 Example 7 82% VCAP-co-18% VOH BGE/H₂O 0.610.5 >2880 24 Example 7 82% VCAP-co-18% VOH BGE/H₂O 0.3 10.5 >2800 25Example 8 82% VCAP-co-18% VOH BGE 0.6 10.5 >2800 26 Example 8 82%VCAP-co-18% VOH BGE 0.3 10.5 >2800 27 Example 11 82% VCAP-co-18% VOHIPA/H₂O 0.6 10.5 >2800 28 Example 12 74% VCAP-co-26% VOH BGE/H₂O 0.610.5 >2800 29 Example 13 66% VCAP-co-34% VOH BGE/H₂O 0.6 10.5 >2800 30Example 14 66% VCAP-co-34% VOH BGE/H₂O 0.6 10.5 2800 *ΔT_(sc):subcooling temperature difference

While the invention has been described with particular reference tocertain embodiments thereof, it will be understood that changes andmodifications may be made which are within the skill of the art.Accordingly, it is intended to be bound only by the following

1. A polymer derived at least from: (A) one N-vinyl amide unit, and (B)one hydroxyl-containing acrylate unit selected from the group consistingof polyethylene glycol acrylate, polyethylene glycol methacrylate,2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate, 3-hydroxypropylacrylate, and blends thereof.
 2. The polymer of claim 1 wherein saidN-vinyl amide is selected from the group consisting of:N-vinyl-2-pyrrolidone; N-vinyl-2-caprolactam; piperidone;N-vinyl-3-methyl pyrrolidone; N-vinyl-4-methylpyrrolidone;N-vinyl-5-methylpyrrolidone; N-vinyl-3-ethyl pyrrolidone;N-vinyl-3-butyl pyrrolidone; N-vinyl-3,3-dimethylpyrrolidone; N-vinyl-4,5-dimethylpyrrolidone; N-vinyl-5,5-dimethylpyrrolidone;N-vinyl-3,3,5-trimethylpyrrolidone; N-vinyl-5-methyl-5-ethylpyrrolidone; N-vinyl-3,4,5-trimethyl-3-ethyl pyrrolidone;N-vinyl-6-methyl-2-piperidone; N-vinyl-6-ethyl-2-piperidone;3,5-dimethyl-2-piperidone; N-vinyl-4,4-dimethyl-2-piperidone;N-vinyl-6-propyl-2-piperidone; N-vinyl-3-octyl piperidone;N-vinyl-7-methyl caprolactam; N-vinyl-7-ethyl caprolactam;N-vinyl-4-isopropyl caprolactam; N-vinyl-5-isopropyl caprolactam;N-vinyl-4-butyl caprolactam; N-vinyl-5-butyl caprolactam;N-vinyl-4-butyl caprolactam; N-vinyl-5-tert-butyl caprolactam;N-vinyl-4-octyl caprolactam; N-vinyl-5-tert-octyl caprolactam;N-vinyl-4-nonyl caprolactam; N-vinyl-5-tent-nonyl caprolactam;N-vinyl-3,7-dimethyl caprolactam; N-vinyl-3,5-dimethyl caprolactam;N-vinyl-4,6-dimethyl caprolactam; N-vinyl-3,5,7-trimethyl caprolactam;N-vinyl-2-methyl-4-isopropyl caprolactam; N-vinyl-5-isopropyl-7-methylcaprolactam; and blends thereof.
 3. The polymer of claim 1 that isderived at least from: (A) one N-vinyl amide selected from the groupconsisting of N-vinyl-2-caprolactam, N-vinyl-2-pyrrolidone, and blendsthereof; and (B) one hydroxyl-containing acrylate unit selected from thegroup consisting of: polyethylene glycol methacrylate, polyethyleneglycol acrylate, 2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate,3-hydroxypropyl acrylate, and blends thereof.
 4. The polymer of claim 1derived at least from: (A) about 1% to about 99% of at least one N-vinylamide unit, and (B) about 1% to about 99% of a hydroxyl-containingacrylate unit selected from the group consisting of polyethylene glycolacrylate, polyethylene glycol methacrylate, 2-hydroxyethyl acrylate,3-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, and blendsthereof.
 5. A polymer derived at least from two different units: (A)N-vinyl-2-caprolactam or one of its derivatives, and (B) onenon-acrylate unit having: (i) at least one hydroxyl group, and/or (ii)at least one functional group convertible to a hydroxyl group wherein atleast one group is converted to hydroxyl functionality in the finalpolymer product.
 6. The polymer of claim 5 wherein said derivative isselected from the group consisting of: N-vinyl-3-methyl-2-caprolactam;N-vinyl-4-methyl-2-caprolactam; N-vinyl-7-methyl-2-caprolactam;N-vinyl-3,5-dimethyl-2-caprolactam; N-vinyl-3,7-dimethyl-2-caprolactam;N-vinyl-4,6-dimethyl-2-caprolactam,N-vinyl-3,5,7-trimethyl-2-caprolactam; N-vinyl-7-ethyl-2-caprolactam;N-vinyl-4-isopropyl-2-caprolactam; N-vinyl-5-isopropyl-2-caprolactam;N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-butyl-2-caprolactam;N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-tert-butyl-2-caprolactam;N-vinyl-2-methyl-4-isopropyl-2-caprolactam;N-vinyl-5-isopropyl-7-methyl-2-caprolactam;N-vinyl-4-octyl-2-caprolactam; N-vinyl-5-tert-octyl-2-caprolactam;N-vinyl-4-nonyl-2-caprolactam; and N-vinyl-5-tert-nonyl-2-caprolactam,and blends thereof.
 7. The polymer of claim 5 wherein said non-acrylateunit is a polymerizable unit.
 8. The polymer of claim 7 wherein saidpolymerizable unit is selected from the group consisting of: vinylacetates, vinyl esters, alkenyl halides, vinyl carboxylic acids, vinylketones, vinyl aldehydes, epoxides, co-hydroxy alkenes, vinyl phenols,and blends thereof.
 9. The polymer of claim 7 wherein said polymerizableunit is selected from the group consisting of: vinyl acetate; ethylvinyl acetate; isopropenyl acetate; methyl vinyl acetate;(pent-2-en-3-yl)acetate; 2-acetoxy-2-butene;2-acetoxy-3-methyl-2-butene; vinyl hexanoate; vinyl octanoate; vinylpropionate; vinyl N-valerate; 1-chloro-1-butene; 1-chloro-2-butene;3-chlorocrotonic acid; 3-chloro-methacrylic acid; 1-chloro-2-pentene;2-chloro-2-butene; 2-chloro-3-methyl-butene; 2-chloro-3-hexene;2-chloro-2-pentene; 4-chloro-prop-3-en-2-one; 1,2-dichloroethylene;trichloroethylene; vinyl chloride; vinylidene chloride, and theirbromine and iodine analogues; acrylic acid; 2-butenoic acid; cinnamicacid; 2,3-dimethylacrylic acid; 3,3-dimethylacrylic acid;2,3-dimethyl-2-butenoic acid; 2-ethylacrylic acid; 2-ethyl-2-butenoicacid; fumaric acid; methacrylic acid; 2-pentenoic acid; 4-pentenoicacid; ethyl vinyl ketone; 2-hepten-4-one; hex-3-ene-2-one;4-hexen-3-one; 3-methyl-3-penten-2-one; 4-methyl-3-penten-2-one;5-methyl-1-hexen-3-one; methyl vinyl ketone; 3-penten-2-one; propylvinyl ketone; but-2-enal; 2-butenedial; 3-butyn-1-al; cinnamic aldehyde;2-methyl-2-butenal; 2-methylene butyraldehyde; 2-methyl-2-pentenal;2-methyl-2-propenal; 3-methylbut-2-enal; 2-pentenedial; prop-2-enal;1,2-epoxybutane; 2,3-epoxybutane; ethylene oxide; propylene oxide;isobutylene oxide; allyl alcohol; 3-buten-1-ol; 2-vinyl phenol; 3-vinylphenol; 4-vinyl phenol; and blends thereof.
 10. The polymer of claim 5wherein said non-acrylate unit is a solvent.
 11. The polymer of claim 10wherein said solvent comprises at least one hydroxyl group.
 12. Thepolymer of claim 11 wherein said solvent is selected from the groupconsisting of: butanol, 2-butanol, ethanol, ethylene glycol, methanol,1-propanol, 2-propanol, propylene glycol, 2-butoxyethanol,2-ethoxyethanol, 2-isopropoxyethanol, 2-methoxyethanol,2-propoxyethanol, and blends thereof.
 13. The polymer of claim 5 derivedat least from: (A) N-vinyl-2-caprolactam, and (B) vinyl acetate whereinsaid acetate after polymerization has been partially or completelyhydrolyzed.
 14. The polymer of claim 5 derived at least from: (A) about1% to about 99% of N-vinyl-2-caprolactam, and (B) about 1% to about 99%of one unit having at least one hydroxyl group and/or a unit having atleast one functional group convertible to a hydroxyl group.
 15. Thepolymer of claim 1 or claim 5 that is degradable.
 16. A composition thatcomprises said polymer of claim 1 or claim
 5. 17. The composition ofclaim 16 that further comprises at least a solvent, gas hydrateinhibitor, biocide, corrosion inhibitor, salt, emulsifier,de-emulsifier, defoamer, lubricant, rheology modifier, or shale swellinginhibitor.
 18. The composition of claim 17 wherein said solvent isselected from the group consisting of: water, 2-butoxyethanol, ethanol,methanol, ethylene glycol, monoethylene glycol, 1-butanol, 2-butanol,1-propanol, 2-propanol, propylene glycol, 2-ethoxyethanol,2-isopropoxyethanol, 2-methoxyethanol, 2-propoxyethanol, and blendsthereof.
 19. An oilfield applications polymer derived at least from: (A)one N-vinyl amide, and (B) one unit comprising: (i) at least onehydroxyl group, and/or (ii) at least one functional group convertible toa hydroxyl group wherein at least one group is converted to hydroxylfunctionality in the final polymer product.
 20. The oilfieldapplications polymer of claim 19 having a molecular weight from about500 amu to about 10,000 amu.
 21. The oilfield applications polymer ofclaim 19 that is a gas hydrate inhibitor, anti-agglomerant, shaleswelling inhibitor, and/or scale inhibitor polymer.
 22. A compositioncomprising the oilfield applications polymer of claim
 19. 23. Thecomposition of claim 22 that further comprises at least a solvent, gashydrate inhibitor, biocide, corrosion inhibitor, salt, emulsifier,de-emulsifier, defoamer, lubricant, rheology modifier, or shale swellinginhibitor.
 24. The polymer of claim 19 derived at least from: (A) about1% to about 99% of N-vinyl-2-caprolactam, and (B) about 1% to about 99%of one unit having at least one hydroxyl group and/or a unit having atleast one functional group convertible to a hydroxyl group.
 25. Anoilfield applications polymer derived at least from: (A)N-vinyl-2-caprolactam, and (B) hydroxyethyl methacrylate.
 26. Anoilfield applications polymer derived at least from: (A)N-vinyl-2-caprolactam, and (B) vinyl acetate wherein said acetate afterpolymerization has been partially or completely hydrolyzed.
 27. A methodfor preventing, retarding, and/or reducing the formation and/or growthof gas hydrates that comprises: (I) selecting a polymer derived at leastfrom: (A) one N-vinyl amide-based unit, and (B) one unit comprising: (i)at least one hydroxyl group, and/or (ii) at least one functional groupconvertible to a hydroxyl group wherein at least one group is convertedto hydroxyl functionality in the final polymer product; and (II)introducing a composition comprising said polymer into apetroleum-containing fluid from about 0.01% to about 3% of said polymerbased on the weight of the water present in said petroleum-containingfluid being treated.
 28. A method for preventing, retarding, and/orreducing the formation and/or growth of gas hydrates that comprises: (I)selecting a polymer derived at least from: (A) N-vinyl-2-caprolactam,and (B) hydroxyethyl methacrylate, and (II) introducing a compositioncomprising said polymer into a petroleum-containing fluid from about0.01% to about 3% of said polymer based on the weight of the waterpresent in said petroleum-containing fluid being treated.
 29. A methodfor preventing, retarding, and/or reducing the foiniation and/or growthof gas hydrates that comprises: (I) selecting a polymer derived at leastfrom: (A) N-vinyl-2-caprolactam, and (B) vinyl acetate that afterpolymerization has been partially or completely hydrolyzed; and (II)introducing a composition comprising said polymer into apetroleum-containing fluid from about 0.01% to about 3% of said polymerbased on the weight of the water present in said petroleum-containingfluid being treated.